Polar polymer with charged sites

Another approach to reducing the EOF as well as wall adsorption is to add a compound to the running buffer that will compete with the solute for the silanol sites on the surface. These materials must have some affinity for the charged or polar sites on the inner wall and so they must, themselves, be hydrophilic or charged. Nonionic surfactants are hydrophilic to prevent solute adsorption on the wall and block the silanols in order to reduce the EOF. The use of cationic polymers in the buffer results in a reversal of EOF to the anodic direc-... 

It is expected that the electron-transfer reactivity in a macromolecular domain is strongly influenced by the primary structure of polymer matrices, distribution of redox sites, charge density and polarity of polymer domain, etc. In order to assess these factors, the electron-transfer reaction of poly(xylyl-viologen) (5) with Fe(III) ion was selected for investigation. 

Because enzymes are polyionic polymers, it is expected that pH will affect most of their properties. In fact, change in pH may change the distribution of charges in the active site and in the whole surface of the protein molecule. Enzymes may present polar amino acid residues at its active site whose charge depends on pH. With respect to enzyme activity, it is a well known fact that rates of enzyme catalyzed reactions tend to decrease at extremes of pH usually exhibiting maxima at some intermediate values as shown in Fig. 3.10 for the case of glucoamylase (Illanes 1983). 

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